First Trimester Screening



Deborah explains the Nuchal Translucency Scan

More information about First Trimester Screening:

All women have a small chance of having a baby with a physiological disability or syndrome, such as Down Syndrome. The First Trimester Pregnancy Scan Screening Package is a risk assessment test to determine whether your chances of having a baby with Down Syndrome (Trisomy 21), Edward’s Syndrome (Trisomy 18) and Patau Syndrome (Trisomy 13) are high or low.

The components of First Trimester Screening include:

  • Maternal age
  • Presence or absence of major fetal abnormalities on ultrasound
  • Nuchal Translucency (fluid measurement behind the fetus’ neck)
  • The level of two proteins in your blood (Free-ß-hCG and PAPP-A)

Accuracy and timing for First Trimester Screening

Some clinics provide a one-stop (OSCAR) 11 or 12 week assessment whereby the counselling, scan and blood tests take place on the same day. The detection rate of Down’s Syndrome with OSCAR at 12 weeks is about 90%.

We use an alternative system, which is recommended by the Fetal Medicine Foundation, whereby the blood tests are carried out at 10 weeks and the scan is performed at 12 weeks. It has been estimated that this approach increases detection rates up to 94%. This requires 2 separate visits but we feel that it is important to achieve the highest accuracy that we can.

(If you are unable to plan your appointments this way, the blood tests can be performed 10 weeks 0 days – 13 weeks 6 days, and the scan can be performed 11 weeks 2 days – 13 weeks 6 days).

Please feel free to give us a call and request to speak to a sonographer if you have any questions about the Nuchal Translucency Scan or First Trimester Screening.